1. Field of the Invention
The teachings provided herein relate to the preparation and uses of compositions comprising extracts of Astragalus membranaceus. 
2. Description of Related Art
A decrease in the number of platelets or megakaryocytes is a condition known as thrombocytopenia, a condition experienced in a number of diseases, as well as treatments that suppress bone marrow function, suppress hematopoiesis, or cause a reduction in platelet count or megakaryocytes. Cancer patients, for example, are often treated with chemotherapy or radiation therapy and experience thrombocytopenia, increasing their risk of bleeding and potentially limiting the dose of the chemotherapeutic agent. There are at least two mechanisms that create thrombocytopenia—(1) a mechanism that reduces the production of megakaryocytes or platelets; and (2) a mechanism that acts to breakdown or remove the platelets from the circulation.
An example of a disease that uses the second mechanism is idiopathic thrombocytopenic purpura (ITP). ITP is an autoimmune hematological disease that is characterized by an attack by the immune system that destroys platelets in the blood, resulting in an abnormally low platelet count. The platelet destruction is due to the presence of antiplatelet autoantibodies, which are antibodies directed against the patient's own platelets. This low platelet count can lead to easy bruising, bleeding gums and, less commonly, to severe internal bleeding. Bleeding from the nose, gums, gastrointestinal or urinary tracts may also occur, and bleeding within the brain is a rare but feared complication.
Currently, ITP affects approximately 200,000 people in the United States, and there is no known cure. About half of all cases are classified as “idiopathic,” meaning the cause is unknown. The term “thrombocytopenic” refers to the decrease in platelets, and the term “purpura” refers to the purplish areas in the skin and mucous membranes, such as the mouth lining, where bleeding has occurred due to the decreased platelets. The term “immune thrombytopenic purpura” is often used to describe the condition, as it specifies the immune nature of the disease and includes cases having known causes as well as cases of unknown origin.
ITP can be triggered by drugs, or associated with infection, pregnancy, or immune disorders, such as systemic lupus erythematosus. Acute ITP most commonly occurs in young children. Boys and girls are equally affected, and symptoms often follow a viral infection. About 85% of children recover within 1 year, and the problem does not return. ITP is considered chronic when it lasts more than 6 months, and the onset of chronic ITP can occur at any age. ITP peaks in adulthood and females are affected two to three times more often than males. Unfortunately, lifestyle changes are often required to prevent bleeding due to injury.
In some embodiments, standard ITP treatments use high-dose corticosteroids. Patients respond to the high-dose corticosteroids, but the responses are not durable, and the treatments are poorly tolerated with significant side-effects. And, failure or intolerance to corticosteroids can lead to the choice of a splenectomy, as the spleen is the major site of platelet destruction which, of course, leads to additional complications. In some embodiments, treatments can include administration of prednisone and/or IV immune globulin. Other drugs such as vincristine, azathioprine (IMURAN), DANAZOL, cyclophosphamide, and cyclosporine can also be used.
One of skill in the art will appreciate that abnormally low platelet counts are known to result from treatment with chemotherapeutic drugs or radiation treatments. These treatments provide the first mechanism described above in that they suppress bone marrow function, reduce the production of megakaryocytes and, in turn, reduce the platelet count. In contrast, the abnormally low platelet counts of ITP result from the second mechanism that removes platelets from the circulation through the creating of antibodies that bind to the platelets. Accordingly, those of skill in the art will appreciate a composition that can treat thrombocytopenia regardless of whether it's due to a damaged biological process of creating the megakaryocytes or platelets in the circulation, or due to the antibody-mediated mechanism of ITP.